Electromagnetic brake



C. B. MILLS. ELECTROMAGNETIC BRAKE. APPLICATION FILED MAR. 1, 1917.

Patented Feb. '15, 1921..

WITNESSES AT.TORNEY UNITED STATES PATENT OFFICE.

CHESTER B. MILLS, OF EAST MGKEESPORT, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AN SYLVANIA.

MANUFACTURING COMPANY, A CORPORATION OF PENN- ELECTROMAGNETIC BRAKE;

Specification or Letters Patent.

Patented Feb. 15;, 1921.

Application filed March 1, 1917. SeriaLNo. 151,869.

' citizen of the United States,

the county of of East McKeesport, in

gheny and State of Pennsylvania,

vented a new and useful Electromagnetic Bralres,

lowing is a specification.

of which the and a resident Allehave in Improvement in fol- My invention relates to electromagnetic brakes for hoisting apparatus and similar mechanisms, and it has for its object to provide a simple and convenient means for adjusting brakes to compensate dent to their use and thus for wear incimaintain proper conditions for efiicient operation. t

In the operation ofbrakes that are controlled by electromagnets,

it is necessary, at

intervals, to adjust the relative positions of certain of the parts in order to ma ntain the proper relation between the armature members of the electromagnets and the stationary portions of the latter.

The normal po- 'sition of the movable member of an electromagnet varies, thinner because of wear, to increase the air-gap operating stationary initial pull exerted by the materially decreased.

as the brake shoes become in such manner as between it and the comember, whereby the electromagnet is.

In a brake constructed in accordance with my invention,

the usual brake levers are pivotally mounted upon a base or support- 111 member.

An electromagnet operates thi ough the usual lever mechanism to efiect disengagement of the brake shoes from the wheel with which they shoes become thinner coact. As the brake because of wear, the

air gap between the relatively movable; parts of the electromagnet increases and the initial pull of the electromagnet corresponding degree.

The changes in the relative positions of the brake are comthe movable parts of pensated for by means of whereby the points of pivotal support of the is decreased to a an arrangement brake shoes are shifted relatively to each other and to the stationary ber. The shifting means or screw rovidedwith bot left-ham screw threads.

supporting memcomprises a bolt h right-hand and The rotation of the screw-threaded member operates to increase or decrease the dist points of pivotal support,

ance between the according as the member is rotated in the one or the other direction.

In the accompanying drawing, the single figure is a view, partially in elevation and partially in section, of a brake mechanism constructed in accordance with my invention.

A brake wheel 1 is mounted on a shaft'2 which may be connected to any suitable mechanism (not shown) such, for example,

as an elevator motor or a hoist motor.

- wheel 1 is provided with a suitable periphtoggle mechanism 8 and a pivotally mounted lever 9.

Each of the levers 5 is pivotally supported by a pin 10. Each of the pins 10 is pivotally connected to. a base member-'11 by means of a link 12 and a pin 13. The positions of the pins 10, relatively to each other and to the pins 13, are adjustedas desired by a bolt or screw 15 that is provided with right-hand and with left-hand screw threads at itsrespective end portions. The bolt 15 is retained in any position to which it may be adjusted by a stop member 16 that is in alinement therewith. The stop member 16 resists the torque exerted upon the brake mechanism when the latter-is applied to the rotating wheel-1. t

The stop member 16 may be adjusted longitudinally. and it is retained in its adjuste position by means of a locking nut 17. looking member 18, which is pivotally mounted adjacent to the opposite end of the dso bolt 15, is provided with a rectangular recess 19 for coacting with an end portion 20 of thebolt 15 that is of rectangularcross section. The locking member 18 thus prevents not only longitudinal movement of the bolt 15, but, also, such rotation as might, otherwise, be caused by 5 are normally held in such position that the brake shoes 4 are in engagement with the shocks or jars incident tothe operation of the brake. The brake levers .pins 10 to approach each other.

During the operation of the brake, the bearing portions, or linings, of the brake shoes 4 wear away and the levers 5 normally occupy positions nearer the wheel 1 than is the case when the brake shoes 4 are in normal condition. The result is to cause the end of the lever 9 that is connected to the toggle mechanism 8 to assume a position that is lower than that normallyoccupied by it. The'outer end of the lever 9 and the armature member 6 carried by it, assume positions at a constantly increasing distance from the electromagnet 7. If such abnormal conditions. are permitted to continue, the length of the air-gap between the relatively movable parts of the electromagnet may "increase to such affect the operationof the brake. F urthermore, the efliciency of the brake is materially decreased. Y To adjust'the brake mechanism to oompensate for the wear of the brake shoes, the adjusting screw 22 is actuated to remove the stress upon the springs 21. An adjusting screw 23 of the locking member 18 is turned to permit rotative movement of the member 18 in a clockwise direction about its point of pivotal support, The rectangular portion 20 of the bolt 15 is then disengaged from the recess 19 and the bolt may be turned by any suitable device such, for example, as a wrench for engaging the portion 20. The bolt 15 is turned to cause the This movement is permitted by the links 12 which are pivotally connected to the stationary pins 13.

When the levers 5 occupy such positions that the air-gap of the'electromagnet is of proper length, the bolt 15 is again locked in position by the locking member 18. The springs 21 are then placed under stress by the adjusting nut 22. While the pivot pins 10 are moved through an 'arc that is not concentric with the wheel 1, the clearances between the engaging ortions of the several parts are such that t e brake shoes 4' may conform to the surface of the wheel in. the positions to which'they are adjusted. This operation may be repeated whenever the wear of the brake shoes .is such as to render a ,change in the length of the air-gap of the electromagnet necessary or advisable.

he arrangement whereby the ositions of the brake levers may beadjuste to thereby vary the length of the air-gap of the controlling electromagnet afiords a convenient method of quickly correcting abnormal conditions obtaining inthe brake mechanism. It is possible, also, to employ the linings for the brake shoes for a materially longer period than is'possible in brakes of ordinary construction which do not embody adjusting or compensating devices.

From the above, it will be obvious that the adjusting mechanism renders the operation degree as to seriously.

porting means therefor,

, ance with the prior art.

I claim as my invention:

1.. The combination with a relatively stationary member having a pair of pivotalsupports and a pair of relatively movable brake levers each having a pivotal support, of a pair of links respectively connecting said first-named supports to said secondnamed supports, and means for adjusting the positions of said second-named supports with respect to said first-named supports.

2. The combination with a supporting member, a magnet supported thereby having an armature member normally separated therefrom by an air gap, levers each having a brake shoe, of a pair of links connecting said brake levers to said supporting member, a pair of links connecting said brake levers to each other and to said armature member, and means for adjusting the phsitions of said brake levers, to compensate for the wear of said brake shoes and to maintain the length of said air gap substantially constant.

3. In a brake mechanism, the combination with'a brake lever, a power-device operativelyconnectedthereto, and a source of power for actuating said power device, of means for adjusting the position of said brake lever and thereby adjusting the position of the movable portion of said power device to maintain said power device in a and a link pivotally connected to said stationary member and to said lever, of means, comprising a screw-threaded member, for adjusting the position of said link relatively to said stationary member and means for locking said screw-threaded member.

the combination and pivotal supof means for ad- .justing the positions of the respective supporting means, said means comprising a member provided with both right-hand and left-hand screw-threads.

In 'a brake mechanism, the combination with a brake lever and means for pivotally supporting said brake lever, of means for 6. In a brake mechanism, with a pair of brake levers and a pair of brake adjusted position comprising a member provided with a rectangular recess for engagin said end portion.

11 testimony whereof, I have hereunto 10 subscribed my name this 23rd day of Feb.

CHE STER B. MILLS. 

